Are these 16x5 riveted wheels for a K10 ?

[lapajost]

I wondered if I could get some help ID'ing these wheels. They're 16x5 riveted wheels with 6x5.5 bc, 0 offset, with 6" overall width. I was told they were from a '71 K10.

The stamped numbers/letters common to all the wheels are K-1-1 to the left of the valve stem and CX to the right. All other numbers in the area of the valve stem vary from wheel to wheel. I thought K-1-1 might be the date code but the limited info I found is confusing on that. Any steelie experts out there?